Device for integrating a variable quantity



Feb. 7, 1950 i. E. GROSDOFF 2,496,912

DEVICE FOR INTEGRATING A VARIABLE QUANTITY I Filed May 9, 1946 nu A; W

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w t k N [5 02' E. 6211/1/01? E R Q BY 0&2 A 1 M Q gi s. c A TTl/RNEIPatented Feb. 7, 1950 oavrcr: FOR INTEGRATING A vAnrAnLa QUANTITY IgorE. Grosdoii, Princeton, N. 1., assignor to Radio Corporation of America,a corporation of Delaware Application May 9, 1948, Serial No. 668,441

3 Claims. (Cl. 171-95) This invention relates to devices for integratinga variable quantity such as the volume of sound, the intensity of lightor any other type of variable which may be made to produce an electricalpotential which changes in accordance with the value of such variable.

An important use of the device of the present invention is for theintegration of the applause accorded a speaker or the integration of thenoise incident to some other event. In accomplishing this result, thenoise is picked up by a microphone which generates an alternatingpotential proportional in amplitude to the volume of the sound- Thispotential is amplified, detected and applied to an oscillation generatorwhich delivers an alternating potential having a frequency which variesin accordance with the volume of the sound. The cycles of this variablefrequency potential are counted and indicated either continuously orover a predetermined time interval by an electronic counter. The numberof such cycles indicated during any given time interval varies as thevolume of sound. Likewise the rapidity at which the cycles are countedand indicated in the case of continuous counting also varies as thevolume of the sound. Thus when the volume of the sound is relativelylow, the frequency of the counted cycles has a correspondingly low valueand vice versa.

Various means may be provided for limiting the counting of the cycles toa predetermined time interval following the beginning o1 the noise.Perhaps the simplest of such means would be a timer or a time delayrelay which functions (1) to open a gate between the variable frequencyoscillator and counter in response to the beginning of the noise and (2)to close such gate at a predetermined time after it is opened. Obviouslythe gate may also be opened in response to the beginning of the noiseand closed inresponse to the termination of the noise.

What has been said with respect to the integration of sound is equallyapplicable to the light picked up by a photo cell located to receive thelight admitted through a camera shutter, for example, or to any othervariable which is capable of producing an electrical potential varyingin accordance with the value of the variable.

Important objects of the present invention are (1) the provision of animproved means for integrating a variable quantit and providing aninstantaneous indication of the integrated quantity, (2) the provisionof means for integrating a variable quantity over a p d t r in d e iterval, and (3) the provision 01' an improved device and method ofoperation for deriving and indicating the true integral of a variablequantity in terms of a potential having a frequency which is in directproportion to the value of the variable.

The invention is better understood from the following descriptionconsidered in connection with the accompanying drawing and its scope isindicated by the appended claims.

The single figure of the drawing is for the most part a wiring diagramof the improved integrating device, parts which are old and well knownbeing mostly indicated by boxes bearing legends indicating theircontents.

Referring to the drawing, the integrating device includes a pick-updevice it which ma be a microphone, a photo electric unit or any otherdevice capable of converting variations of a variable to correspondingvariations of an electrical potential.

The electrical potential thus modulated by the variable quantity isamplified by an amplifier II and detected by a detector illustrated asincluding a diode l2, a filter network i3 and an output resistor II.

The detected potential is applied through a lead ii to the input of anoscillator which may be like that disclosed by U. S. Patent 2,321,269.This oscillator functions to make available at its output lead IS apotential having a frequency which is directly proportional to thedetected amplitude or level of the variable quantity picked up by thedevice ill.

The basic element of the oscillator is a fourstep series-capacitorladder network I! driven by a pentode i8. The network ll includes (1)resistors i9, 2| and 22 which are grounded at their low voltageterminals and (2) a resistor 20 which is connected to ground through atriode 23 and a resistor 24. With the resistor 20 open circuited by thetriode 23, the fundamental frequency of the oscillator is 2000 cyclesand, with the resistor 20 grounded, it is somewhat over 4000 cycles.Values of resistance between zero and infinity in series with theresistor 20 will produce frequencies between these limits. The actualvalue of this series resistance is of course determined by the amplitudeof the detected potential applied to the input of the tube 23.

The resistors 26 and 25 form a center tap 58 on the 3 supply voltage.The triode 21 functions as an anode resistor for the triode 23. Thus ifthe triode 23 is at zero bias, it draws full anode current through thetriode 21 and the two tubes form a low resistance to ground. As negativebias is applied to the grid of the triode 23 through the phase reverser28 the equivalent plate resistance of the tube 23 is increased and theoutput frequency at the oscillator output lead It is lowered in directproportion to such increase.

The output potential of the oscillator is applied to the second grid ofa mixer tube 25. To the first grid of the tube 29 may be applied asquare topped timing wave produced by a timing device 30 which isconnected to the detector output lead i so as to be actuated in responseto the beginning of a detected variable-quantityresponsive potential. Asa result, there is applied through the lead 3] a potential which (1) hasfrequencies determined by the values of the integrated variable quantityand (2) is restricted to a predetermined time interval by the wavedelivered from the timer 50 but only when a switch 32 is in its closedposition.

This potential, having its frequency modulated in accordance withsuccessive values of the variable quantity, is applied through a waveshaping or impulse generating device 55 and a lead 54 to the input of anelectronic counter which may include a plurality of trigger circuitunits 35 to 44. Impulse generating device 31 produces, in lead 34, asuccession of negative pulses, one for each cycle of the substantiallysinusoidal output voltage of the oscillator appearing at output terminall6.

Each of these trigger circuits is of the type where in a pair of triodeelements each has its anode coupled to the grid of the other so thatstable conditions are established only when current conductivity is inone or the other of the triode elements. Current conductivity istransferred from one to the other of the triodes (1) in response to anegative pulse applied to the common anode terminal. (2) in response toa positive pulse applied to the grid of a triode element which is notconducting current, or (3) in response to the application of a negativepulse to the grid of a triode which is conducting current.

Thus the trigger circuit 35, for example, 1) has its anodes connected tothe +13 lead through a common resistor and through individual resistors46 and 41, (2) has a cathode which is grounded and common to both triodeelements, (3) has its anodes cross connected to its grids through acapacitor 48 which is shunted by a re-- sistor 49 and a capacitor sowhich is shunted by a resistor 5| and (4) has negative bias potentialapplied to its grids either directly from a negative bias lead 54, whichis connected to a suitable bias potential source (not shown), or fromthe lead 54 through a reset switch 53 and a reset lead 52. Forindicating when current conductivity is in the left hand triode element,an indicator 55 such as a neon lamp is connected across the resistor 45.

The other trigger circuits 3. to 44 are like the trigger circuit 35 andtherefore need not be described in detail.

By opening and closing the reset switch 53, there is established astandby condition of the counter with current conductivity in the righthand triodes of all the trigger circuits. Negative pulses. one for eachcycle of the oscillator output potential, are applied to the commonanode terminal of the trigger circuit 35.

The first of these negative pulses transfers current conductivity to theleft hand side of the trigger circuit 35, thereby lighting the lamp 55and indicating a count of one cycle. The second pulse transfers currentconductivity to the right hand triode of the trigger circuit 35 andproduces a negative pulse which is transmitted through a capacitor 55 tothe common anode terminal of the trigger circuit 35 and functions totransfer current conductivity to the left hand triode, this triggercircuit thereby lighting an indicating lamp 51. How additional negativepulses applied to the lead 34 are indicated by the counter is too wellknown to require further explanation.

It is apparent that the count is made in the binary numerical system, sothat the lamps lighted at the end of the count indicate different powersof two, which must be added together to derive the equivalent value inthe decimal system. Thus, the lamp 55 indicates 1 cycle, the lamp 5!indicates 2 cycles, the third lamp 4 cycles. This number of cycles isrepresented by the binary number Ill and by the decimal number I.

By providing a somewhat different indicating system, the counter may bemade to indicate the total number of cycles directly in the decimalsystem.

By way of example, the decimal counter may be 'of the type disclosed inthe copending application of Igor E. Grosdoif, Serial No. 580,446,filing date March 1, 1945, entitled Improvement in electron counter,"and assigned to the same assignee as the instant application.

What the invention provides is an integrating device which functions tointegrate a variable quantity and to provide an instantaneous indicationof the integrated variable quantity.

I claim as my invention:

1. In combination. an oscillation generator continuously producing asubstantially sinusoidal alternating output voltage the frequency ofwhich may be varied, means responsive to the instantaneous value of asporadic variable quantity for varying the frequency of said voltage inproportion to such instantaneous value, means coupled to said voltageoutput for producing therefrom a voltage pulse for each cycle of saidvoltage, means for counting and indicating the total number of saidpulses, and means responsive to the initial appearance of said variablequantity for limiting the counting of the number of said pulses to apredetermined time lnterval immediately following said appearance.

2. In combination. a pick-up device operable in response to a variablequantity to produce a potential having an amplitude proportional to theinstantaneous value of said quantity, means for detecting and rectifyingsaid potential, an oscillation generator continuously producing acyclically-recurring continuously-varyin alternating output voltage thefrequency of which may be varied, means for varying the output frequencyof said generator in accordance with the amplitude of said detected andrectified potential, and means for counting and indicating the totalnumber of cycles of said generator output frequency during apredetermined time interval.

3. In combination. a pick-up device operable in response to a sporadicvariable quantity to produce a potential having an amplitudeproportional to the instantaneous value of said quantity, means fordetecting and rectifying said potential, an oscillation generatorcontinuously producing a substantially sinusoidal alternating outputvoltage the frequency of which may be varied, means for varying theoutput frequency of said generator in accordance with the amplitude ofsaid detected and rectified potential, means for counting and indicatingthe total number of cycles of said generator output frequency, andtiming means responsive to the initial appearance of said variablequantity for limiting to a predetermined time interval immediatelythereafter the 5 supply of said generator output to said counting Numberand indicating means. 2,341,040 IGOR E. GROSDOFF. 2,353,203 2,384,792REFERENCES CITED 5 2 337 49 The following references are of record inthe 230559 file of this patent: 2330439 2,438,425 UNITED STATES PATENTSNumber Name Date 10 1,809,683 Fitzgerald June 9,1931 Number 2,309,749Baughman Feb. 2, 1943 144,131 2,325,927 Wilbur Aug. 3, 1943 Name DateHathaway Feb. 8, 1944 Usselman July 11, 1944 Brown Sept. 18, 1945Cornelius Oct. 23, 1945 Miller Aug. 13, 1946 Peterson Nov. 4, 1947 VanceMar. 23, 1948 FOREIGN PATENTS Country Date Austria Dec. 27, 1935

